Sealing station with a product protection plate

ABSTRACT

The disclosure relates to a sealing station with a product protection plate fastened thereto, wherein a fastening mechanism used for fastening the product protection plate comprises a magnetic locking unit, a hook-in locking unit or a gravity locking unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims foreign priority benefits under 35 U.S.C. § 119(a)-(d) to German patent application number DE 102021110382.7, filed Apr. 23, 2021, which is incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a sealing station.

BACKGROUND

Such a sealing station is known from DE 10 2012 006 696 A1 and DE 10 2018 114 263 A1. The product protection plates used within these sealing stations, which are arranged on the lower side of a sealing plate, have the function of reducing the heat emitted by the sealing plate onto the product placed in deep-drawing troughs or packaging trays.

It is known to fasten product protection plates from below by means of countersunk screws to the sealing plate positioned thereabove. During operation of the sealing station, the screw heads positioned on the lower side of the product protection plate can heat up. This can lead to the formation of visually undesirable marks on the top film of the sealed packages as a result of the sealing process. In order to alleviate this problem, in practice the screw heads facing the top film are covered with a silicone. However, the silicone cannot completely prevent marks from being left on the top film.

In addition, product protection plates are detachably fastened to the sealing plate for cleaning or maintenance work, so that silicone applied over the screw head makes it difficult to install and dismantle a product protection plate. On the one hand, this is due to the fact that the silicone must first be scraped off in a time-consuming process in order to dismantle the product protection plate. On the other hand, a new silicone must be applied after the product protection plate has been reinstalled. The associated curing time extends the downtime of the tool, which leads to increased idle times of the packaging machine.

The use of temperature-resistant screws made of plastic can also leave marks on top films. Screwing the product protection plates on the side facing away from the top film significantly increases the installation and service effort. It has also been found that sinking the countersunk screws into recessed bores formed on the lower side of the product protection plate still allows the product protection plate to be installed and dismounted from the front, however these bores can also leave marks on the top film. A further problem with such bores is that product residues can accumulate in them, which impairs hygienic standards.

SUMMARY

In view of the problems described in connection with the prior art, it is an object of the disclosure to provide a sealing station with a product protection plate, by means of which it is possible to produce packaging which is flawless, particularly from the optical point of view.

The disclosure relates to a sealing station for a packaging machine, which is provided in particular in the form of a deep-drawing packaging machine or in the form of a tray-sealing machine. The sealing station according to the disclosure has a sealing tool lower part for receiving deep-drawing troughs or packaging trays and a sealing tool upper part positioned above it with at least one heatable sealing plate. The sealing plate is configured to seal the deep-drawing troughs or packaging trays received by the sealing tool lower part with an upper film, wherein at least one product protection plate is fastened to a lower side of the sealing plate. Its function is to reduce heat transfer from the sealing plate to the product to be packaged. The sealing tool upper part has at least one fastening mechanism for detachably fastening the product protection plate to the lower side of the sealing plate. This allows the product protection plate to be dismantled for service or cleaning purposes, for example.

According to the disclosure, the fastening mechanism between the sealing plate and the product protection plate comprises at least one magnetic locking unit for generating a magnetic holding force for fastening the product protection plate to the sealing plate, at least one hook-in locking unit for fastening opposite outer sides of the product protection plate to areas of the sealing plate facing them, or at least one gravity locking unit which is configured to lock the product protection plate to the sealing tool upper part by means of a gravitational force exerted by the product protection plate in the mounted state and pointing away from the sealing plate positioned above it.

The fact that the fastening means proposed in accordance with the disclosure are formed between the sealing plate and the product protection plate, i.e., on opposite sides thereof, means that the lower side of the product protection plate facing away from the sealing plate and towards the upper film remains free of mounting means and thus does not need to have any bores for such mounting means. Consequently, the lower side of the product protection plate can be provided with a flat surface that leaves no marks on the upper film.

The three above-mentioned alternatives for fastening the product protection plate according to the disclosure can be implemented easily and cost-effectively on the sealing station from a structural point of view. Furthermore, the respective alternatives enable the product protection plate to be installed and dismantled quickly and easily at the sealing station. Above all, however, it is possible to avoid marks on the top or lid film. Furthermore, the fastening alternatives according to the disclosure allow idle times of the sealing station to be reduced, since the product protection plate can be installed and dismantled at the sealing station without great effort, in particular within a short time.

Preferably, the magnetic locking unit has at least one permanent magnet that is fastened to the sealing plate or to the product protection plate. The permanent magnet could, for example, be fastened to a lower side of the sealing plate facing the product protection plate, in particular centrally above the product protection plate. Such a permanent magnet can be manufactured at low cost and can be integrated as a functional component in a compact manner at the sealing station.

It is conceivable that several permanent magnets are fastened to the lower side of the sealing plate, in particular according to an evenly distributed arrangement. This can bring technical assembly advantages for the product protection plate.

A preferred variant provides that the magnetic locking unit comprises at least one component made of a soft magnetic material (hereinafter also referred to as “soft magnetic component”), which is fastened to the sealing plate or the product protection plate. Provided that this component is fastened to the product protection plate, the permanent magnet is fastened to the sealing plate and vice versa. When the product protection plate is installed at the sealing station, the permanent magnet and the component made of a soft magnetic material may be positioned opposite each other to provide a desired holding force for fastening the product protection plate to the sealing plate.

It is conceivable that, in the assembled state of the product protection plate, the permanent magnet has a trough-like centering recess facing the soft magnetic component, in which at least part of the soft magnetic component is held in a form-fitting manner. The permanent magnet and the soft magnetic component together form a centering unit. The centering recess can be oval-shaped in particular. This allows the product protection plate to be fastened to the sealing plate in a manner that is stable in terms of position.

According to an embodiment of the disclosure, the permanent magnet and/or the component made of the soft magnetic material have at least a partial plastic coating. This enables a smooth and noise-reduced installation and dismantling of the product protection plate at the sealing station.

One variant provides for the permanent magnet and the component made of the soft magnetic material to be fully embedded in plastic. This full coating has the advantage that manufacturing tolerances can be better compensated and prevents mechanical stresses in the magnetic components.

A preferred variant provides that the permanent magnet or the component made of the soft magnetic material is fastened inside a recess formed on the sealing plate. This favors a flat assembly of the sealing plate and the product protection plate. In this way, if necessary, shortened stroke cycles can be achieved during operation of the sealing station.

It is conceivable that in the assembled state the soft magnetic component is fastened by screwing to an upper side of the product protection plate facing the sealing plate, wherein a part of the soft magnetic component projecting from the upper side of the product protection plate forms a negative shape to the centering recess formed in the permanent magnet. Their respective shapes can be non-rotatable relative to each other. Thus, it is possible for the permanent magnet together with the soft magnetic component to form a centering unit to fasten the product protection plate to the sealing plate in a predetermined position and alignment.

Preferably, the sealing plate forms a receptacle on its lower side shaped to receive the product protection plate. In the assembled state, this results in a flat, cassette-like module.

According to a preferred variant, the hook-in locking unit has at least one hook-in projection formed on a first outer side of the product protection plate and at least one elastic locking bracket arranged on a second outer side of the product protection plate opposite the first. The fastening means displaced to opposite outer sides of the product protection plate allow easy installation and dismantling of the product protection plate at the sealing station. The hook-in projection can be hooked within an indentation of the sealing plate. The locking bracket can lock onto a projection of the sealing plate.

According to an embodiment, the hook-in projection is integrally formed on the product protection plate, i.e., integrally formed therewith. In particular, the elastic locking bracket can be screwed to the product protection plate on its upper side facing the sealing plate.

Preferably, the locking bracket has a locking tongue that can engage the projection formed on the sealing plate to secure the hooked product protection plate to the sealing plate. It is conceivable that the elastic locking bracket can be released from a state locked to the sealing plate by means of a screwdriver so that the product protection plate can be easily dismantled from the sealing station by an operator, for example for service, cleaning and/or conversion measures.

In the two variants of the locking mechanism described above, i.e., the magnetic locking unit and the hook-in locking unit, it would be possible for at least one spacer to be positioned between the sealing plate and the product protection plate in the assembled state. Preferably, the spacer is arranged on the sealing plate within the receptacle formed thereon for receiving the product protection plate, for example screwed securely therein. A preferred variant provides a total of four spacers distributed within the mounting recess around the permanent magnet fixed therein.

A preferred embodiment provides that the gravity locking unit is configured to unlock the product protection plate in the dismantled state of the sealing tool upper part, when the latter is turned upside down, by merely pushing the product protection plate in the direction of gravity. Such a gravity locking mechanism may be in the form of a push-to-open locking mechanism, wherein pressing in this variant may be facilitated by the gravitational force of the product protection plate to bring it into an unlocked state for detachment.

It is possible that the gravity locking unit has at least two ball-shaped locking bodies. It is conceivable that these two balls are received within guide bores formed on the sealing plate, which also form part of the gravity locking unit. These guide bores can be such that the two balls tend to move toward each other for locking the product protection plate and tend to move apart for unlocking the product protection plate. For this purpose, the guide bores can have a bore cross section that tapers towards the product protection plate.

One variant provides that the product protection plate has at least two centering bolts on its upper side and the sealing plate has two corresponding centering bores. The centering bolts make it easier to install and dismantle the product protection plate at the sealing station.

In an embodiment, the gravity locking unit has a bolt in the form of a countersunk screw fastened to the product protection plate, which can be inserted head first into a mounting opening formed on the sealing plate to secure the product protection plate to the sealing plate. The head shape formed on the bolt can be secured to the gravity locking unit by means of the two balls.

Preferably, the product protection plate has a lower side facing the sealing tool lower part in the assembled state with a surface free of bores. The flat surface thus facing the product prevents marks from forming on the lid film.

The disclosure further relates to a packaging machine which is in the form of a deep-drawing packaging machine or in the form of a tray-sealing machine (also known as a “tray-sealer” in specialist circles) and has a sealing station in accordance with the disclosure. On such a deep-drawing packaging machine, deep-drawing troughs can be sealed with an optically flawless lid film. The same applies to a tray sealer on which the sealing station according to the disclosure is used, in particular a product protection plate by means of the fastening mechanism according to the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the disclosure are explained in more detail below with reference to Figures. In detail:

FIG. 1 shows a perspective view of a deep-drawing packaging machine;

FIG. 2 shows a perspective view of a tray sealing machine;

FIG. 3 shows a sealing tool upper part with a magnetic locking unit for a product protection plate;

FIG. 4A shows a sealing plate with a product protection plate fastened to it by means of a magnetic locking unit;

FIG. 4B shows the product protection plate of FIG. 4A in isolated view;

FIG. 4C shows the sealing plate of FIG. 4A in isolated view;

FIG. 5A shows a sealing plate with a product protection plate fastened to it by means of a hook-in locking unit;

FIG. 5B shows the product protection plate of FIG. 5A in isolated view;

FIG. 5C shows the sealing plate of FIG. 5A in isolated view;

FIG. 6A shows a sealing tool upper part with a gravity locking unit for a product protection plate;

FIG. 6B shows the sealing tool upper part of FIG. 6A turned upside down to dismantle the product protection plate;

FIG. 6C shows the sealing tool upper part of FIG. 6B with the gravity locking unit unlocked;

FIG. 6D shows the sealing plate and the product protection plate in the disassembled state; and

FIG. 7 shows a sealing tool upper part with several pairs of sealing product protection plates mounted on it.

Identical components are identified throughout the Figures by the same reference signs.

DETAILED DESCRIPTION

FIG. 1 shows a packaging machine which is in the form of an intermittently operating deep-drawing packaging machine 1. This deep-drawing packaging machine 1 has a forming station 2, a sealing station 3, a transverse cutting device 4 and a longitudinal cutting device 5, which are arranged in this order in a transport direction R on a machine frame 6. On the input side, a feed roller 7 is located on the machine frame 6, from which a lower film 8 is drawn off. Furthermore, the deep-drawing packaging machine 1 has a transport chain 11, in particular two transport or clamp chains 11 arranged on both sides, which grips the lower film 8 and transports it further in transport direction R per main working cycle.

In the embodiment shown, the forming station 2 is configured as a deep-drawing station in which deep-drawing troughs T are formed into the lower film 8 by deep-drawing, for example by means of compressed air and/or vacuum. The forming station 2 can be configured such that several deep-drawing troughs T are formed next to one another in the direction perpendicular to the transport direction R. A filling path 12 is provided downstream of the forming station 2 in the transport direction R, in which the deep-drawing troughs T formed in the lower film 8 are filled with product.

The sealing station 3 has a hermetically sealable chamber 3 a in which the atmosphere in the deep-drawing troughs T can be evacuated and/or replaced by gas purging with an exchange gas or a gas mixture before sealing with the upper film 10 dispensed from an upper film receptacle 9.

The transverse cutting device 4 can be configured as a die cutter which cuts the lower film 8 and the upper film 10 in a direction transverse to the transport direction R between adjacent deep-drawing troughs T. The upper film 10 and the lower film 8 are cut in the same direction. The transverse cutting device 4 operates in such a way that the lower film 8 is not cut across its entire width, but is not cut through at least in an edge region. This enables controlled onward transport through the transport chain 11.

The longitudinal cutting device 5 can be configured as a knife arrangement with which the lower film 8 and the upper film 10 are cut between adjacent deep-drawing troughs T and at the lateral edge of the lower film 8 in the transport direction R, so that separated packages are present downstream of the longitudinal cutting device 5.

The deep-drawing packaging machine 1 also has a control system 19, which has the task of controlling and monitoring the processes running in the deep-drawing packaging machine 1. A display device 20 with operating elements 21 is used to visualize or influence the process sequences in the deep-drawing packaging machine 1 for or by an operator.

FIG. 2 shows a tray sealing machine 12, which is also known as a tray sealer in expert circles. At the tray sealer 12, packaging trays V are provided on a feed belt 13. The tray sealing machine 12 has a gripper device 14, by means of which the packaging trays V provided on the feed belt 13 are picked up and transferred for a tray sealing process to a sealing tool lower part 15 of the sealing station 16. During the tray sealing process, the sealing tool lower part 15 is raised against a sealing tool upper part 17 a positioned above it in order to seal the packaging trays V with an upper film 18 guided through the sealing station 16. After the sealing process, the sealing station 16 is opened by lowering the sealing tool lower part 15. Now the sealed packages V can be picked up by means of the gripper device 14 and transferred to a discharge conveyor 19.

FIG. 3 shows a sealing tool upper part 17 b in isolated representation. The sealing tool upper part 17 b is suitable for use on the deep-drawing packaging machine 1 shown in FIG. 1. The sealing tool upper part 17 a of FIG. 2 and the sealing tool upper part 17 b of FIG. 3 may have a comparable structure, at least as far as the present disclosure is concerned. In the following, however, reference will be made primarily to the deep-drawing packaging machine 1.

The sealing tool upper part 17 b of FIG. 3 includes a sealing plate 20. The sealing plate 20 forms a sealing surface 21 that presses the upper film 10 against the deep-drawing troughs T during the sealing process to produce a sealing seam for closing the deep-drawing troughs T.

Furthermore, FIG. 3 shows that a product protection plate 23 is fastened to a lower side 22 of the sealing plate 20. According to its designation, the product protection plate 23 has the function of protecting a product to be packaged. The product protection plate 23 positioned between the sealing plate 20 and the product to be packaged functions as a heat block to reduce heat transfer from the sealing plate 20 to the product to be packaged.

In FIG. 3, the product protection plate 23 is fastened to the lower side 22 of the sealing plate 20 by means of a magnetic locking unit 24. The magnetic locking unit 24 has a permanent magnet 25 arranged in a recess 26 formed on the lower side 22 of the sealing plate 20. Further, the magnetic locking unit 24 has a component 27 made of a soft magnetic material fastened to an upper side 29 of the product protection plate 23. The permanent magnet 25 exerts a holding force H on the component 27 made of the soft magnetic material positioned thereunder to fasten the product protection plate 23 to the lower side 22 of the sealing plate 20.

FIG. 3 also shows that two spacers 31 are arranged between the sealing plate 20 and the product protection plate 23 positioned below it. Above the sealing plate 20, the sealing tool upper part 17 b has a heating device 28.

FIG. 4A shows the sealing plate 20 and the product protection plate 23 assembled in isolated view. According to FIG. 4A, the permanent magnet 25 is recessed on the lower side 22 of the sealing plate 20, i.e., firmly received within the recess 26 formed therein. Within the recess 26, the permanent magnet 25 may be embedded in plastic K, or possibly even completely enclosed by it. The plastic K can completely line the recess 26.

The component 27 made of the soft magnetic material forms an integral part of the product protection plate 23. In the assembled state, the product protection plate 23 shown in FIG. 4A has a lower side 33 facing the upper film 10 with a bore-free surface 34. This means that the product protection plate 23 does not leave any visually unattractive marks on the upper film 10 when the deep-drawing cavities T are sealed.

The magnetic locking unit 24 shown in FIG. 4A is configured as a centering unit for fastening the product protection plate 23. For this function, the permanent magnet 25 has a centering recess 30 facing the soft-magnetic component 27, which receives an upper part 32 of the soft-magnetic component 27, which is correspondingly configured as a negative shape, in a form-fitting manner. The sealing plate 20 forms a receptacle 42 for the product protection plate 20. This receptacle 42 may be such that, when assembled, the surface 34 of the product protection plate 23 and the sealing surface 21 formed on the sealing plate 20 are substantially flush.

FIG. 4B shows the product protection plate 23 in isolated view. The soft magnetic component 27 is screwed to the upper surface 29 of the product protection plate 23. The product protection plate 23 has a flat structure, with the plate-like portion having a height of about 0.5 cm to 2.0 cm.

FIG. 4C shows a perspective view of the sealing plate 20 in isolated view. The sealing plate 20 of FIG. 4C is configured to receive the product protection plate 23 shown in FIG. 4B. Four spacers 31 are arranged within the receptacle 42. Together with the magnetic locking unit 24, these ensure that the product protection plate 23 assumes a predetermined alignment when installed on the sealing plate 20.

FIG. 5A shows a hook-in locking unit 35 for the product protection plate 23. This hook-in locking unit 35 comprises two hook-in projections 36 formed on a first outer side 37 of the product protection plate 23. An elastic locking bracket 39 is arranged on a second outer side 38 of the product protection plate 23, which is opposite to the first outer side 38. The elastic locking bracket 39 is configured to engage a protrusion 40 formed on the sealing plate 20 when locked. In order to unlock the elastic locking bracket 39, a screwdriver can be inserted into a recess 43.

By means of the hook-in locking unit 35 shown in FIG. 5A, the product protection plate 23 can be effortlessly hooked onto the sealing plate 20 at indentations 44 formed thereon and latched onto the projection 40 on the opposite side by means of the locking bracket 39. Due to the fact that the hook-in projections 36 and the elastic locking bracket 39 are formed on opposite outer sides 37, 38 of the product protection plate 23, the lower side 33 of the product protection plate 23 can be completely flat, i.e., free of bores, so that during operation of the deep-drawing packaging machine 1, no visually unappealing marks are made on the upper film 10 guided underneath during the sealing process.

FIG. 5B shows the product protection plate 23 from FIG. 5A in isolated representation. The elastic locking bracket 39 has a hook shape and is fastened to the upper side 29 of the product protection plate 23 such that its locking tongue 45 is above the recess 43.

FIG. 5C shows the sealing plate 20 in isolated view. The sealing plate 20 has a sealing flange 46 extending all around. Thereon, on opposite sides, are formed the indentations 44 for the hooking projections 36 as well as the projection 40 for the locking bracket 39.

FIG. 6A shows the sealing tool upper part 17 b with a gravity locking unit 50 for the product protection plate 23. The gravity locking unit 50 has two ball-shaped locking bodies 51 (hereinafter referred to as “balls 51”), which are movable within guide bores 52. The balls 51 hold a bolt 53 that is fastened to the top 29 of the product protection plate 23. The gravity locking unit 50 has an assembly opening 60 for receiving the bolt 53. The bolt 53 is in the form of a countersunk screw and is locked within the assembly opening 60 by means of the balls 51 at its countersunk head. Further, two centering bolts 54 are fastened to the top surface 29 and are inserted into centering bores 55 of the sealing plate 20. This can provide a useful mounting guide for the product protection plate 23.

FIG. 6B shows the sealing tool upper part 17 b of FIG. 6A turned upside down to dismantle the product protection plate 23. The product protection plate 23 is moved further towards the sealing plate 20 in the direction of gravity G. The bolt 53 thus pushed further into the assembly opening 60 and the guide bores 52, which become larger in cross-section, allow the balls 51 to move downward past the head shape of the bolt 53 into the guide bores 52. This is shown in FIG. 6B and FIG. 6C.

According to FIG. 6D, the product protection plate 23 can be lifted out of the sealing tool upper part 17 b. The installation of the product protection plate 23 can be carried out in the installed state of the sealing tool upper part 17 b at the sealing station 3 by inserting the bolt 53 from below upwards into the assembly opening 60, whereby the bolt 53 is locked by means of the balls 51.

FIG. 7 shows a sealing tool upper part 17 b with a plurality of product protection plates 23A, 23B, 23C, 23D fastened thereto, which can be fastened by means of one of the previously described locking mechanisms.

The alternative fastening mechanisms for the product protection plate 23 described in advance in FIGS. 3 to 6D can be used on both the deep-drawing packaging machine 1 and the tray-sealing machine 12. 

What is claimed is:
 1. A sealing station for a packaging machine, wherein the sealing station comprises a sealing tool lower part for receiving deep-drawing troughs or packaging trays and a sealing tool upper part positioned thereabove with a heatable sealing plate which is configured to close the deep-drawing troughs or packaging trays received by the sealing tool lower part with an upper film, wherein a product protection plate is fastened to a lower side of the sealing plate, and wherein the sealing tool upper part comprises a fastening mechanism for releasably fastening the product protection plate to the lower side of the sealing plate, wherein the fastening mechanism between the sealing plate and the product protection plate comprises at least one magnetic locking unit for generating a magnetic holding force for fastening the product protection plate to the sealing plate, at least one hook-in locking unit for fastening opposite outer sides of the product protection plate to regions of the sealing plate facing the product protection plate, or at least one gravity locking unit which is configured to lock the product protection plate to the sealing tool upper part by means of a gravitational force exerted by the product protection plate in an assembled state and pointing away from the sealing plate positioned above it.
 2. The sealing station according to claim 1, wherein the fastening mechanism comprises the at least one magnetic locking unit, and the at least one magnetic locking unit comprises at least one permanent magnet fastened to the sealing plate or to the product protection plate.
 3. The sealing station according to claim 2, wherein the at least one permanent magnet has at least partially a plastic coating.
 4. The sealing station according to claim 2, wherein the at least one permanent magnet is completely embedded in plastic.
 5. The sealing station according to claim 2, wherein the at least one permanent magnet is fastened inside a recess formed on the sealing plate.
 6. The sealing station according to claim 1, wherein the fastening mechanism comprises the at least one magnetic locking unit, and the at least one magnetic locking unit comprises at least one component made of a soft magnetic material, which is fastened to the sealing plate or to the product protection plate.
 7. The sealing station according to claim 6, wherein the at least one component made of the soft magnetic material has at least partially a plastic coating.
 8. The sealing station according to claim 6, wherein the at least one component made of the soft magnetic material is completely embedded in plastic.
 9. The sealing station according to claim 6, wherein the at least one component made of the soft magnetic material is fastened inside a recess formed on the sealing plate.
 10. The sealing station according to claim 1, wherein the fastening mechanism comprises the at least one hook-in locking unit, and the at least one hook-in locking unit comprises at least one hook-in projection formed on a first outer side of the product protection plate and at least one elastic locking bracket formed on a second outer side of the product protection plate opposite to the first outer side.
 11. The sealing station according to claim 1, wherein the fastening mechanism comprises the at least one gravity locking unit, and the at least one gravity locking unit is configured to unlock the product protection plate in a dismantled closed state of the sealing tool upper part, when the sealing tool upper part is turned upside down, by merely pressing the product protection plate in a direction of gravity.
 12. The sealing station according to claim 1, wherein the product protection plate has at least two centering bolts.
 13. The sealing station according to claim 1, wherein the product protection plate has a lower side facing the sealing tool lower part in the assembled state and having a surface free of bores.
 14. The sealing station according to claim 13, wherein the product protection plate has at least two centering bolts.
 15. A packaging machine, which is a deep-drawing packaging machine or a tray-sealing machine, comprising the sealing station according to claim
 1. 